Githyanki Empire
For millennia the people who would be come known as the Gith were slaves and servants of the Illithid Mind Flayers, psychic parasites and sinister manipulators. A leader emerged among the Gith and lead them into open rebellion against their oppressors and eventually their freedom was won. The Illithid Inquisition was shattered and the thousands-of-thousands of colony worlds were liberated. However, where there was once order, there was now chaos; the Gith were riven into the war-hawkish Githyanki and the peaceful Githzerai. The Githyanki started an empire of their own, led by Empress Vlaakith I. One pact with the Dragon God Tiamat later and red dragon riding Githyanki became a symbol of destruction and war throughout the cosmos.
The Githyanki spend the vast majority of their lives on the Astral Sea, where no mortal creature ages or dies, only entering a Wildspace to lay their eggs and raise their children. Because of this it is almost impossible to say how old any one Githyanki truly is, let alone say the age of the Empire, but the last Empress to be coronated was Empress Vlaakith CLVII, who has lead her people for at least the last 1000 years, a suspiciously long life even among Githyanki leaders. The Githyanki control enormous swaths of the Astral Sea and prey indiscriminately on anyone who dares be foolish enough to come too close to their territory, knowingly or not. Githyanki warbands are a common peril out on the Silver Sea, even in the farthest throws of the Reach.
Recently...
Recent events on Toril, in a city named Baldur's Gate, have left the Illithid Inquisition in tatters, and sparked a civil war between Githyanki. The civil war has grown to be massive, but is quite well contained within Githyanki territory. Many systems that used to be controlled by the Githyanki have been abandoned as fleets and clans have fallen back into the depths of their most centralized worlds to rally behind their chosen banners. This massive retreat in particular has proven to be extremely fruitful for pirates and treasure hunters, far more so than in any other time in known history -- the Githyanki Empire was built upon the bones of the Illithid, and their empire was built on something even older. Tombs, artifacts, lost worlds and civilizations, for the first time in millennia are accessible from under the retreating leathery boot of the Githyanki. There be dragons, and there be gold for those brave or curious enough to take it -- somehow, even the junk has buyers everywhere.